BIODIVERSITAS ISSN: 1412-033X Volume 21, Number 12, December 2020 E-ISSN: 2085-4722 Pages: 5685-5689 DOI: 10.13057/biodiv/d211226 An assessment of the reproduction, predation, and nesting behavior of Sulawesi Masked-owl (Tyto rosenbergii) in oil palm plantation: A case study of West and Central Sulawesi, Indonesia ADE NENDI MULYANA1,♥, SWASTIKO PRIYAMBODO2,♥♥, HERMANU TRIWIDODO2, HENNY HENDARJANTI3, BANDUNG SAHARI3,4 1Program of Integrated Pest Management, Graduate School, Institut Pertanian Bogor. Jl. Raya Dramaga, IPB University Campus, Bogor 16680, West Java, Indonesia. Tel.: +62-251-8622642. ♥email: [email protected] 2Department of Plant Protection, Faculty of Agriculture, Institut Pertanian Bogor. Jl. Meranti, IPB University Campus Dramaga, Bogor 16680, West Java, Indonesia. Tel.: +62-251-8622642, ♥♥email: [email protected] 3PT. Astra Agro Lestari Tbk. Pulogadung Industrial Area, East Jakarta 13920, Jakarta, Indonesia 4Center for Transdisciplinary and Sustainability Science, Institut Pertanian Bogor. Jl. Raya Dramaga, IPB University Campus, Bogor 16680, West Java, Indonesia Manuscript received: 16 August 2020. Revision accepted: 21 November 2020. Abstract. Mulyana AN, Proyambodo S, Triwidodo H, Hendarjanti H, Sahari B. 2020. An assessment of the reproduction, predation, and nesting behavior of Sulawesi Masked-owl (Tyto rosenbergii) in oil palm plantation: A case study of West and Central Sulawesi, Indonesia. Biodiversitas 21: 5685-5689. The quality and quantity of yield in palm plantations are reduced due to inevitable factors such as pests, diseases, and weeds. Furthermore, owls (Tytonidae) play a role as potential predators to control rats, the major pest. Therefore, this study aims to observe the reproduction patterns, predation, and nesting behavior of Tyto rosenbergii. To achieve this, direct observation and the installation of a camera trap in the nest box was adopted. Furthermore, a predation test was carried out by feeding the owls with rats daily in a cage measuring 4m x 8m x 6m. The results showed that the number of eggs produced ranged from 2 to 6, with an average of 3.85. Also, the Percentage of hatching ranges between 0-100% with an average of 80.77%, and that of chicks that survive to the fully feathered is 51%. In addition, T. rosenbergii was able to prey on 1-4 rats per night, and its activity mostly occurs outside the cage than inside, except when they had a reproductive season. Keywords: Biological control, eggs, nest box, predator, prey INTRODUCTION commodities such as rice and oil palm. They are active at night to hunt rats, small animals, and other wild birds Indonesia is the world's largest palm oil producer, with (Rabou 2019). This species has a wide distribution (Taylor an export contribution of 55.78% (Oil World 2019). One of 1994), with small mammals being the dominant prey the biggest obstacles in the production process is the (Hovarth et al. 2018; Milchev 2015; Syaufi et al. 2020; infestation of rats at all oil palm plantation stages, Marti 2010) and are bred in oil palm plantation by making including nurseries, immature, and mature plants. The nest box. This is evident to Bank et al. (2019) that the symptom of rat attack on oil palm fruit is in the form of cut installation of the nest box is a measure in maintaining the marks. Furthermore, the estimated loss due to this attack owl population. Furthermore, artificial buildings provide ranges from 5-10% of the total yield (Wood and Fee 2003). suitable nesting sites for various bird species (Mainwaring Meanwhile, the dominant rat species found in oil palm 2015), especially with feed availability. Nest boxes are plantations are Rattus tiomanicus and R. tanezumi generally made of wood and are installed in the middle of (Verwilghen 2015; Ikhsan et al. 2020). an oil palm plantation. Also, Barn owls are very selective Various efforts to manage rats in oil palm plantations in choosing the nest box to be occupied (Abidin et al. include technical, physical, mechanical, sanitary, 2016). According to Wendt and Johnson (2017), owls are biological, and chemical control. Furthermore, synthetic more attracted to wooden boxes because they are similar to chemical rodenticides' continuous use to manage rats has natural nesting cavities in trees. negative impacts, which causes resistance (Horak et al. The use of T. alba is currently a recommendation for rat 2015) and leads to wrong target because they are eaten by control in oil palm plantation because it is proven to be non-target animals/organisms (Elliot et al. 2014). To effective in suppressing fruit damage below the economic overcome this, many rat control in oil palm plantation threshold (Rajagukguk 2014). However, local species' use uses Tyto alba, a natural enemy of rats by providing nest also needs attention, especially in the Sulawesi region, boxes on oil palm plantation for this species to live and which has a different owl species. Tyto rosenbergii breed. (Sulawesi Masked-owl), a close relative of the Barn owl (T. Tyto alba is one of the Tytonidae family species, which alba) but has a relatively larger body size, is endemic is widely bred to control rat pests in various agricultural Sulawesi Island. 5686 BIODIVERSITAS 21 (12): 5685-5689, December 2020 The habitat of this includes rainforests, shrubs, forested case, the variable observed was the number of rats that areas near human settlements, grasslands, and cultivated were preyed on per night. areas such as plantations (BirdLife International 2016). However, only a few studies have reported T. Nesting behavior study of Sulawesi Masked-owl (Tyto rosenbergii to control rat pests in an oil palm plantation in rosenbergii) Sulawesi. Therefore, the available information is still The nesting behavior of T. rosenbergii was observed to limited to its biology and ability to prey on rats. determine the presence and activity of owls in the nest box. Consequently, this study focused on examining the This was made based on three criteria: nest box without reproductive patterns, predation, and nesting behavior of eggs and chicks, eggs, and chicks. The observations were the Sulawesi Masked-owl (T. rosenbergii) in oil palm made using a camera trap, set on video mode and mounted plantations. The results are expected to become a reference inside the nest box. Each criterion was chosen by three nest for using the Sulawesi Masked-owl (T. rosenbergii) as a boxes with observations on each for 72 hours (3 x 24 biological control agent for rat pests in an oil palm hours). Each video was 10 seconds long with 10-minute plantation in Sulawesi. intervals between videos. Data analysis MATERIALS AND METHODS The data is processed in tabulated form and graphs using Microsoft Excel 2016 and then described. Time and place of research Furthermore, the correlation between the number of eggs The research was conducted from July 2019 to January per nest box and the success rate of the chicks to mature 2020 in an oil palm plantation located in Towiora Village, was analyzed by Pearson correlation using Minitab 2016. Rio Pakava District, Donggala Regency, Central Sulawesi and Martasari Village, Pedongga District, Pasangkayu Regency, West Sulawesi. RESULTS AND DISCUSSION Reproduction study of Sulawesi Masked-owl (Tyto Reproduction study of Sulawesi Masked-owl (Tyto rosenbergii) rosenbergii) Observation of reproductive patterns was carried out From a total of 55 nest boxes observed, 22 (40%) were directly in the nest box at the study site. Nest boxes are being in the breeding phase (unhatched eggs). Furthermore, generally built in the middle of oil palm plantations as 104 oval and white eggs were observed from 22 nest boxes. breeding houses for Sulawesi Masked-owl. They are made The number of eggs produced in a reproductive period of wood, measuring 1m x 0.5m x 0.6m. In this study, 55 ranges from 2-6 per nest box with an average of 3.85 (SD = nest boxes spread over 16 plantation blocks with a total 0.98) as shown in Figure 1. Schott (2016), reported that the area of 529.53ha were observed. Also, the observed number of T. rosenbergii eggs produced in one variables include reproductively active nest boxes, namely reproduction ranges from 2-3. the number of nest boxes with unhatched eggs, number of Factors that play an important role in breeding owls eggs per nest box, hatching of eggs, and hatching interval include food availability, weather (Chausson et al. 2013) between eggs in the same nest box. Furthermore, and habitat conditions, predation risk, agricultural observations were made every two days when the eggs activities, diseases, and nest box placement (Adejumo were not hatched every two days. However, when one egg 2019). Furthermore, the number and quality of eggs has hatched, the rest are observed daily until all the eggs produced are influenced by nutritional factors during the hatch to see the hatching interval between eggs. formation period (Nager 2006). When food is abundant, birds reproduce well. However, in conditions of food Chicks growth and development shortage, the female owls sometimes do not lay eggs at all The development of T. rosenbergii chick was seen (Taylor 1994). from the time the eggs hatches until it is fully feathered and able to fly (8 weeks old). The variables observed were the number and age of chicks that died and those that survived until eight weeks. Observations were carried out directly on the nest box at intervals of once a week. Predation rate of Sulawesi Masked-owl (Tyto rosenbergii) The test to determine the predation level was carried out on three owls taken from the field. The criteria for (%) rcentage Pe testing the owls is the ability to fly and hunt their prey. The test was carried out on a 4 m x 8 m x 6 m cage containing nest boxes. Before this, the owls were adapted in the test cage for two weeks and each individual was tested for four Number of eggs per nest box days by feeding with a minimum of five rats daily.